JPH06294626A - Inspection equipment for printed wiring board - Google Patents

Abstract

PURPOSE:To provide an inspection equipment for printed wiring board in which a true hole mask image can be formed at low cost by detecting a through hole accurately. CONSTITUTION:The inspection equipment comprises an inspecting section for selecting a true defect data based on a hole mask image and a pattern image from an image pickup unit for reading out a wiring pattern on a printed wiring board 19, a hole recognition mask processing section 4, and a data totalization means 33. The hole recognition mask processing section 4 comprises a section 44 for deciding a hole based on a hole recognition effective signal and a hole measurement signal from a hole measuring/recognizing section 41 and outputting a hole detection signal, a section 45 for producing a hole mask image, a memory section 42 for recording hole position information, and a section 43 for receiving hole position information from the hole information memory section and transmitting a hole recognition effective signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed wiring board inspecting apparatus capable of masking an erroneous inspection caused by a land shape of a through hole without missing a pattern defect near the through hole.

[0002]

2. Description of the Related Art A large number of wiring patterns including lands of through holes are formed on a printed wiring board. This wiring pattern may have a defective shape due to disconnection, short circuit, chipping, dust adhesion, etc. during the manufacturing process. Therefore, various inspection devices have been proposed for detecting such defect shapes.

This inspection device is an image pickup device such as a CCD camera for reading a wiring pattern on a printed wiring board and an A for converting an analog signal of the image pickup device into a digital signal.
It has an A / D converter and an inspection unit for detecting a defect shape from the digital signal. As this inspection unit, there is a unit that uses the feature extraction method for the inspection algorithm. By the way, the defect shape may occur not only in the lead wire portion of the wiring pattern but also in the land around the through hole.

FIG. 20 shows a state of a land 92 provided around the through hole 91 and a lead wire 93 connected to the land 92. And FIG. 20 (A)
Indicates that the land 92 is provided around the through hole 91 in a normal state. FIG. 20 (B),
The land 92 shown in (C) is formed off the center of the through hole 91.

In the cases of FIGS. 20B and 20C, it is usually judged that there is a defect shape. However, Figure 2
In the case of 0 (B), the remaining seat 921 in the land 92
Since there are many lands, the function as a land is fully fulfilled. Therefore, it is not necessary to judge the defect shape. On the other hand, Fig. 2
In the case of 0 (C), there is only half the land 92 around the through hole 91. Therefore, it must be judged as a defect shape.

On the other hand, as described above, the reason why the land 92 is not normally formed around the through hole 91 [FIG. 20 (A)] is that it is difficult to align the two when the wiring pattern is formed by plating. It depends. That is, the printed wiring board before being solidified is usually 40 cm × 50 c
It has a size of about m.

On the other hand, the wiring pattern is 0.05 to 0.5 m
It is formed with a space of m, and the space between through holes is 0.4.
~ 10.0 mm. In addition, the diameter of the through hole is 0.
It is 1 to 5.0 mm. Therefore, if the positioning at the time of the plating deviates from the normal position even slightly, the defect shape of the land as described above occurs.

Therefore, conventionally, there is a method of masking a hole mask image on a land [FIG. 20 (B)] which does not need to be determined as a defect shape during inspection by the above inspection apparatus and does not detect this as a defect shape. It is considered. As the method, for example, "hole position method", "hole recognition method",
There is a "transmitted light method". The contents and problems of these conventional techniques will be described below.

In the above hole position method, the center coordinates of each through hole are measured in advance with reference to NC data for drilling or the hole substrate, and each through hole in the product substrate to be inspected has the center coordinate position. Is to apply a hole mask image. In this method, if the state in which the NC data and the hole center coordinates of the hole substrate and the hole center coordinates of the product substrate are exactly matched can be realized, the hole mask image can be made the same size as the through hole. Since the through holes are masked by the mask image, there is no problem in the inspection on the product board.

The hole board is a copper foil board having only holes. Further, the hole substrate may be a substrate before etching. The center coordinates of the through hole are obtained from the image recognition processing of the hole board image and the NC data for punching the through hole.

However, the above hole position method has the following problems. That is, the above-mentioned center coordinate is 100 between the standard hole board and the actual product board to be inspected.
In many cases, a deviation of about μm occurs. In addition, it is not uncommon for a larger amount of misalignment to occur when the expansion and contraction of products is taken into consideration. That is, as shown in FIG. 21A, in the wiring pattern 9 of the product substrate, the through hole 91 is formed.
Compared to the position of through hole 95 on the hole board,
Misalignment occurs in random directions.

Therefore, as shown in FIG. 21B, when the hole mask image 96 produced based on the hole substrate is applied to the through hole 91 of the pattern image of the product substrate, a deviation occurs between the two. . Therefore, at the time of the inspection by the inspection unit, the residual portion 911 of the land 92 is detected as shown in FIG. Since this residual portion 921 is smaller than the width of the normal wiring pattern,
It is determined that the shape is defective. However, as mentioned above,
Actually, if there is a seat residue 921 of this level, it sufficiently functions as a land.

Therefore, in order not to determine the rest 921 as a defect shape, it is possible to apply an enlarged hole mask image 960 obtained by enlarging the hole mask image as shown in FIG. 21C. However, in this case, although the above problem is solved, the short 933 which is a true defect shape is also masked. As a result, the true defect shape cannot be detected.

Next, the hole recognition method is a method of directly recognizing holes in the product substrate itself which is the object of inspection and applying a hole mask image to the through holes. In this case, since a hole mask image having the same diameter as the hole diameter of the through hole may be applied, there is no false alarm.
In addition, good mask processing that does not miss the defect shape around the through hole is possible.

However, according to this method, holes other than the through holes may be recognized as through holes. In other words, this hole recognition method uses the method of measuring the state continuity of the pattern image, and measures the distance from the center position of the through hole in the product board to the land formed around the through hole to determine the hole center position. Has been set. In more detail, the hole diameter of the through hole existing on the product substrate and the allowable value for it are set in advance, and this method is used to measure whether there is a hole shape that meets the setting conditions.

However, if a simple round shape search is performed by this method, as shown in FIG. 22 (A), if the land 92 is slightly out-of-space, it is not a perfect round shape. I cannot recognize it as a hole. However, particularly in a mini via hole having a small diameter of 0.3 to 0.4 mm, this level of cutout is acceptable as a non-defective product, so it is necessary to recognize it as a hole, perform mask processing, and prevent false alarm output.

Therefore, if a measurement condition is further added and it is determined that "a hole is a hole if the range angle that does not satisfy the" hole radius ± tolerance "viewed from the center of the hole is within a specified range", it is a through hole ". In this method, the hole mask image 96 can be correctly applied to the two through holes 91 as shown in FIG.

However, this method is a method in which the diameter of the land 92, that is, a part of the wiring pattern is measured as described above, and the hole diameter is measured to recognize it as a through hole. Therefore, as shown in FIG.
In the enclosed portion 94 that is enclosed to some extent, such as between the 1,932 and the land 92, all of these are detected as lands, and this enclosed portion 94 is recognized as a through hole. Then, the hole mask image is applied to the surrounding portion 94. Therefore, the reliability of the inspection is reduced.

Next, the transmitted light method is a method of utilizing the transmitted light to perform hole image pickup in synchronization with image pickup of a pattern image and perform hole mask processing based on the obtained hole image. With this method, a hole image can be accurately captured, and minimum mask processing can be performed. Also, the hole image itself can be directly used as the hole mask image. However, in this method, the scale of the dedicated image pickup system for the hole image and the optical system becomes large.

Further, it is necessary to match the hole image and the pattern image, and a high degree of coordinate accuracy between the hole image capturing system and the pattern image capturing system is required. Further, since the transmitted light is used, it is necessary to clean and manage the light transmission table on which the printed wiring board is mounted so that there is no dust or dirt. Therefore, this method is expensive.

[0021]

[Problems to be Solved] As described above, in the hole position method, the position of the through hole can be roughly detected, but the true position of the through hole in the product substrate to be inspected cannot be accurately detected. Further, in the hole recognition method, the position of the through hole on the product substrate is accurate, but if it is attempted to recognize the out-of-place through hole, the surrounding portion of the pattern area is recognized as a through hole and an extra hole mask is generated. Therefore, the inspection reliability is reduced.

Also. The light transmission method can directly use the hole image as a hole mask image, but it is costly and requires high precision and cleanliness control. In view of the above conventional problems, the present invention is to provide a printed wiring board inspection apparatus that can accurately detect through holes to produce a true hole mask image and is low in cost. .

[0023]

The present invention provides a true defect based on an image pickup device for reading a wiring pattern on a printed wiring board which is a product substrate to be inspected, and a pattern image from the image pickup device and a hole mask image described later. The hole recognition mask includes an inspection unit for selecting whether the data is data, a hole recognition mask processing unit provided between the image pickup device and the inspection unit, and a data totaling unit for totaling the defect data. The processing unit measures the continuity of the image at the base material level based on the pattern image and recognizes the hole as a hole measurement recognition unit, the hole measurement signal from the hole measurement recognition unit and the below-mentioned A hole determination unit that inputs a hole recognition valid signal from the hole recognition area generation unit and compares and collates both signals to make a final hole determination and outputs a hole detection signal, and a hole detection unit from the hole determination unit. Input the signal and A hole mask image for making a mask on a hole portion in a pattern image is prepared, and a hole mask generation unit for transmitting the hole mask image to the inspection unit and hole position information indicating the position of the hole on the printed wiring board are recorded. The hole information memory unit and the hole position information of the hole information memory unit are input and expanded by a necessary correction amount, and the hole recognition valid signal for selecting the true hole detection information from the hole measurement signal is input. And a hole recognition area generation unit for transmitting to a hole determination unit.

The most remarkable point in the present invention is that the hole recognition mask processing section is provided with a hole measurement recognition section, a hole information memory section, and a hole recognition area generation section, and the hole measurement symbol and hole recognition from the hole measurement recognition section. The hole recognition valid signal from the area generation unit is input to the hole determination unit to generate a hole detection signal, and the hole mask generation unit generates a hole mask image based on the hole detection signal.

The wiring pattern of the product substrate, which is picked up by the image pickup device, is input to the hole measurement recognition section as a binarized pattern image. The hole measurement recognition unit measures the continuity of the image at the base material level based on the pattern image and recognizes the hole of the through hole. The term "base material level image continuity" means the signal level of the binary image of this portion when the insulating base material in the printed wiring board is imaged by the reflected light method is "base material level" (for example, 0.
When defined as), it means that the pixels at the base material level are continuous in an arbitrary direction. Since the binary image signal level of the hole portion of the through hole is the "base material level", it is necessary to measure this "base material level image continuity" to know the number of continuous pixels. Agree to measure.

As a hole recognition measuring method, for example, there is a radial measuring method shown in the embodiment. There is also a method such as a method in which image measurement is performed vertically in two directions vertically from the main scanning axis, and the results of continuously performing the measurement in the scanning direction are integrated to determine a hole. Further, in the hole measurement, conditions are set so that even if the land is out of place, if it is practically usable as a land, it is recognized as a through hole. Then, the hole recognition information is output to the hole determination unit as a hole measurement signal.

On the other hand, in the hole information memory section, the hole position information indicating the hole position on the printed wiring board is input and the information on the center position of each through hole is recorded.
As the hole position information, data obtained by previously determining the center coordinates of the through hole from the hole substrate or NC data for punching the through hole is used.

This hole position information is information about which diameter of the through-hole is on which part of the product board, and is processed by the hole recognition area generation unit to be described later and sent to the hole determination unit for hole measurement recognition. Collated with the hole measurement signal from the part,
It is used for accurate through hole judgment. In the hole recognition area generation unit, the hole position information in the hole information memory unit is input and this is enlarged according to the required correction amount. And
In the hole determination unit, a hole recognition valid signal for selecting only true hole detection information from the information of the hole measurement signal is created.

In the inspection section, the hole mask image sent from the hole recognition mask processing section and the pattern image of the product substrate are input, and the hole mask image is masked on the pattern image. As described above, a defect shape such as a disconnection, a short circuit, or a chip in the wiring pattern is detected. The pattern image is a binary image. Since this pattern image is synchronized with the delay input of the hole mask image based on the delay of the signal processing in the hole recognition mask processing section, it is preferable that the pattern measurement is delayed in the hole measurement recognition section.

[0030]

In the inspection device of the present invention, the wiring pattern of the product substrate is transmitted to the hole measurement recognition part by the image pickup device. In the hole measurement recognition unit, the hole measurement is performed as described above to recognize the through hole, and the hole measurement signal is input to the hole determination unit.

On the other hand, in the hole information memory section, hole position information indicating the approximate position of the through hole is recorded in advance. Therefore, this hole position information is sent to the hole recognition area generation unit. In the hole recognition area generation unit, this is processed as described above and transmitted to the hole determination unit as a hole recognition valid signal.

In the hole determination unit, the hole recognition valid signal is collated with the hole measurement signal from the hole measurement recognition unit to determine whether the hole indicated by the hole measurement signal is a true through hole. judge. That is, as shown in the above-mentioned conventional example, it is determined whether or not there is an erroneous report such as the surrounding portion of the wiring pattern [FIG. As a result, only true through holes are detected.

Therefore, only the true through hole is sent to the hole mask generation section as a hole detection symbol. Then, in this hole mask generation unit, a hole mask image for masking the through hole is created, and the hole mask image is transmitted to the inspection unit. Next, in the inspection section, the hole mask image is masked with respect to the through holes of the wiring pattern, the defect shape of the wiring pattern is inspected, and the result is sent to a data totaling means such as a display terminal.

In the present invention, the hole measuring and recognizing section measures and recognizes the hole of the product substrate, and the hole deciding section compares it with the hole recognizing valid signal based on the hole position information recorded in advance to make a true determination. Through holes are detected. Therefore, only the true through hole can be picked up, and the false alarm of the through hole does not occur unlike the conventional case.

Therefore, a true hole mask image can be created. Therefore, the minimum hole mask image can be applied only to the necessary portion. Also, the cost is lower than the conventional light transmission method. Therefore, according to the present invention,
A true hole mask image can be created by accurately detecting through holes, and a low cost printed wiring board inspection device can be provided.

[0036]

【Example】

Embodiment 1 An inspection apparatus for a printed wiring board according to an embodiment of the present invention will be described with reference to FIGS. The inspection apparatus uses an image pickup device 21 that reads a wiring pattern 11 on a printed wiring board 10 that is a product board to be inspected, and true defect data based on a pattern image from the image pickup device 21 and a hole mask image described later. An inspection unit 31 for selecting whether there is any, a hole recognition mask processing unit 4 provided between the image pickup device 21 and the inspection unit 31, and a display terminal 33 as a data totaling unit for totaling the defect data. Consists of.

The hole recognition mask processing section 4 has a hole measurement recognition section 41, a hole determination section 44, and a hole mask generation section 45, and also has a hole information memory section 42 and a hole recognition area generation section 43. Between the image pickup device 21 and the hole measurement recognition section 41, an A / D conversion section 22 for converting a captured analog image into a digital signal, and a binarization section for converting this signal into a pattern image of a binary image signal 221 and 221.

Further, the hole recognition mask processing section 4 has a timing generation section 46 for sending a drive clock to each block such as the hole measurement recognition section 41. Moreover, as shown in FIG.
The master CPU 3 is provided between the inspection unit 31 and the display terminal 33.
2. A hole processing CPU section 49 is provided between the master CPU 32 and each block such as the hole measurement recognition section 41.

The function of each block such as the hole measurement recognizing unit 41 will be described later with a concrete example. Here, an outline of the action and effect of the inspection apparatus of this example will be shown. First, the imaging device 21
The wiring pattern 11 picked up at is the A / D converter 22,
After passing through the binarization unit 221, it enters the hole measurement recognition unit 41 as a binary image signal. In the hole measurement recognition unit 41, the through hole in the wiring pattern 11 is measured and recognized, and the hole measurement signal is sent to the hole determination unit 44. On the other hand, in the hole information memory section 42, hole position information obtained from a hole substrate (not shown) is recorded in advance.

This hole position information is expanded in the hole recognition area generation section to become a hole recognition effective signal, and the hole determination section 4
4 is input in synchronization with the hole measurement signal. Then, the two are collated, and the hole detection signal for only the true through hole is sent to the hole mask generation unit 45. Here, a hole mask image is created and the hole mask image is sent to the inspection unit.

Further, the pattern image delayed by the hole measuring and recognizing section 41 is input to the inspection section 31 in synchronization with the hole mask image. Then, in the inspection unit 31, the hole mask image is masked with respect to the through holes of the pattern image and the defect shape in the pattern image is selected, as in the conventional case. The defect data regarding the defect shape is
It is displayed on the display terminal 33 via the master CPU 32.

Next, each block will be specifically described. First, the hole measurement recognition unit 41 measures a through hole based on the input image of the pattern image. As this measurement method, a radial measurement method is used as shown in FIG. According to this method, a portion that is once detected as a through hole 91 is radially measured in eight directions inside the through hole 91 around the measurement center point Y.

Then, a designated radius (for example, 0.2 mm)
Whether or not the land 92 exists within the ± allowable value (for example, 50 μm) is determined for each measurement direction and output. There are eight output lines, and OK (with land) or NG (without land) is output on each output line as shown in FIG. In the above-mentioned NG, as shown in FIG. 2, the land is out of seat and it is determined that there is no land.

That is, 8 of the output lines a to h from the measurement center point
In the book, a to e are OK because there are lands and the distance from the center point to the land satisfies the specified condition, and the rest are NG because there are no lands. Further, as shown in FIG. 3, the output is sent to the hole determination unit as a hole measurement signal.
The pattern image input to the hole measurement recognition unit 41 is
It is subjected to delay processing and transmitted to the inspection unit 31 as a delay pattern image.

The above measurement is performed as shown in FIGS.
Arbitrary pixel extraction is performed from the input image signal, and then FIG.
As shown in FIG. 8, the encoder encodes the pattern of the extracted pixel. In addition, as shown in FIGS. 6 and 7, the lookup table is used to determine the operation unit in each direction based on the pattern code. It is carried out in a series of steps to make a NG judgment.

Now, FIG. 4 shows a circuit portion for performing pixel extraction, which is constructed by combining a line memory and a shift register. Further, FIG. 5 shows the positional relationship of the extracted pixels in the measurement in the eight directions described above in association with the display of FIG.

Basically, the delay in the main scanning direction is constituted by the shift register, while the delay in the sub scanning direction is constituted by the line memory. However, the delay in the multi-stage main scanning direction is constituted by the line memory in order to reduce the circuit scale. Are using. For example, in FIG. 4, among line memories, a5 to a0 and e0 to e6
Is the delay in units of one line in the main scan, and the leading a6
Only one line has a delay. Although a large processing delay occurs due to this pixel extraction process, in order to correct this, the delayed binary image signal is extracted from the end of the line memory section in the sub-scanning direction and output to the inspection system.

Since the position of this binary image signal must finally be matched with the position of the hole mask image, the delay of the hole processing that occurs after this image extraction portion is also calculated, and the final hole mask image is obtained in sub-scanning units. The delay amount is set so as to fit. This is the reason why the line memory is used more than the number of stages required for measurement. In this way, the vertical, horizontal and diagonal extracted pixels necessary for measurement are obtained. After that, the state of this pixel is counted to recognize the through hole.

FIG. 6 shows an outline of the circuit of the measurement and recognition part of the extracted pixel. This circuit is an example in which the look-up table is composed of SRAM. FIG. 7 shows the signal processing of the above hole measurement. The input extracted pixels (a0 to a6) are coded by the encoder, enter the lookup table for determining the radius length of the hole, and are output as OK or NG as the hole measurement signal as described above.

In the encoder, as shown in FIG. 8, the continuous length of the L level portion starting from a0 is coded from the input pixel pattern. In Figure 8, "1"
Indicates the presence of a pattern portion in the extracted pixels a0 to a6. The output code means the count value at the time of first hitting the H level (that is, “1”) when counting the continuous length of the L level portion from the a0 to the a6 direction.

That is, in the above, the extracted pixels arranged in one direction are input to one encoder. Here, the pixel closest to the center of the measurement operator is viewed as the LSB (least significant bit), and continuous zero values (ie,
The number of "L" level pixels) is converted into a binary code and output.

Next, this code value is fetched by the radius length determination lookup table. Only when a code matching the specified radius length tolerance is entered here, 1bi
The output line of t becomes a signal level meaning OK. This will be called a hole measurement signal. Since the determination contents of the look-up table vary depending on the product board, it is preferable to use an SRAM and freely set the "hole processing CPU".

If the number of pixels to be encoded is small, the SRAM logic integrated with the lookup table including the encoder may be used. If the measurement and recognition blocks as described above are provided for eight directions, the hole measurement and recognition unit shown in FIG. 3 is completed. Next, the hole information memory unit 42 will be described. The hole information memory unit stores the hole detection result when the hole substrate is imaged or the hole position information calculated from the NC (numerical control) data at the time of drilling the through hole.

At the time of inspection, data is output under the name of hole center information. This hole information memory section can be configured as a complete bit map type information memory as shown in FIG. However, when the capacity of the hole information memory unit is insufficient with this, the hole center coordinates are mainly stored, and the CP
It is also possible to adopt a configuration in which U or a dedicated DMAC is used to convert and transfer to a bitmap type small capacity buffer.

Next, the hole recognition area generator 43 will be described.
As shown in FIG. 10, the hole recognition area generation unit 43 arbitrarily expands this information signal two-dimensionally based on the hole center information from the hole information memory unit 42 and outputs it as a hole recognition effective signal. Use a spatial filter for

That is, as shown in FIG. 10, for example, with the information resolution set to 100 μm, the hole position information 431 is seen in a pixel and further expanded by 200 μm around the hole center signal. Then, this is made a hole recognition valid signal 432, and this is serially output to the hole determination unit. The enlargement ratio of the hole position information is set to a value according to the amount of deviation between the NC data or the hole position of the hole substrate and the hole position of the product substrate.

Next, the hole determining section 44 will be described. Here, as shown in FIG. 11, a hole measurement signal which is the output of the hole measurement recognition unit 41 (8 bits in this example) and a hole recognition valid signal which is the output of the hole recognition area generation unit (1 bit). When both signals match as an input, it is determined that the hole measurement signal indicates a true through hole, and a hole detection signal is output.

That is, I / I of the hole processing CPU section 49 (FIG. 1)
The O port 3 bit is connected to this block, and it is used as a selection signal for which condition the hole measurement signal in 8 directions is to make the hole determination (1 to 8 lines are regarded as 3 bit code: 0 to 7). At this time, if the number of continuous OK lines is set to 5 (in the case of a 3-bit code, it will be represented as 4), in the case of the through-hole through hole shown in FIG. 2, 5 lines a to e are continuously OK. Therefore, this condition is met.

In addition, if the hole recognition valid signal is valid, that is, if the logic level is 1, it is determined that the hole is a hole, and the hole detection signal is output at the logic level on the "detection" side (hole. Detection signal). Through holes are thus recognized. It should be noted that as the number of continuous OKs is increased, the recognition ability of the out-of-place through-hole decreases, and conversely, the recognition ability is improved.

In the present example, since the hole recognition works only in the vicinity of the hole by the hole recognition effective signal, even if the condition for loosening the seat hole is improved and the through hole through hole detection power is improved, there is a very small risk of causing an incorrect recognition. . Therefore, for example, as shown in FIG. 12 (A), in the mini via hole 910, if the opening angle of the cutout 923 is less than 180 degrees, if it is judged as a good product, the number of continuous OKs should be set to 5, and In this case, misrecognition does not occur.

On the other hand, FIG. 12B shows a mere opening pattern 934, showing an example in which such a pattern is not determined to be a through hole. That is, in this case, the number of continuous OK is 5, and the mini via hole 91 shown in FIG. 12A is used.
Same as 0. However, the hole recognition valid signal input to the hole determination unit at this time should be invalid. That is,
In the NC data and the information from the hole substrate, there is no information indicating the existence of the mini via hole near the opening pattern 934. Therefore, it is not measured and recognized as a through hole.

Next, the hole mask generator 45 will be described. Here, a hole mask image is generated based on the hole detection signal. In the present example, a method using an expanded spatial filter whose circuit scale is large but whose principle is simple will be described with reference to FIG.

The circuit configuration is the same as that of the hole recognition area generation unit 43, and an enlargement frame in the sub-scanning direction is formed in the line memory and an enlargement frame in the main scanning direction is formed in the shift register. Enlargement processing is performed using the output of the shift register as the extracted pixel. The enlargement process itself is performed by the SRAM logic.

A hole mask image is created by expanding the hole detection signal by the hole diameter. Further, the final hole mask image and the pattern image delayed through the hole measurement recognition unit 41 as shown in FIGS.
It is necessary to synchronize with and input. Therefore, in this example, the pattern is aligned with the pattern image in the main scanning direction by delaying by "1 line + α" at the stage of the hole detection signal.
As described above, the alignment in the sub-scanning direction is performed on the binary image (pattern image) side in the hole measurement recognition unit 41.

Next, the hole processing CPU section 49 (FIG. 1) is a CPU for setting the internal conditions of each block in the hole recognition mask processing section 4, communicating with the master CPU, and transferring data. Next, the timing generation section 46 is for generating the operation timing in the hole recognition mask processing section 4. That is, the pixel clock (same as the driving frequency of the image pickup device), the scan enable signal of the image pickup device, the hole processing CPU
Timing is generated based on the three elements of mode setting from the unit 49.

Next, the inspection unit 31 takes in the binary image signal (pattern image) and the hole mask image, and inspects the portion other than the hole mask area. The inspection result is transferred to the master CPU 32 as a defect detection signal. Next, master C
The PU 32 is a CPU that controls the entire apparatus, and the display terminal 33 is a display and operation terminal. These perform operation mode commands to each block, and collect defect information.

Although only one kind of hole processing is performed for the sake of description above, there is actually a need to perform recognition mask processing for a plurality of holes having different diameters. For that purpose, each block is configured as shown below. That is, the hole measurement recognition unit 41 may have one system until the extracted pixels are encoded, but a plurality of radius length determination lookup tables that derive the hole measurement signal from the result are provided. Then, judgments corresponding to different hole diameters are performed in parallel.

Next, the hole information memory unit stores in the memory bit by bit according to the through hole diameter to be processed.
The memory capacity determines the number of holes that can be processed simultaneously. Next, the hole recognition area generation unit needs a processing circuit for each hole type for simultaneous processing. As a result, a hole recognition valid signal for each hole diameter is obtained.

Next, the hole determination unit needs the same kind of holes as the hole recognition area generation unit. There is also a merit that the number of continuous OK can be used properly depending on the hole diameter. Next, the hole mask generation unit requires processing circuits for hole types in the expanded spatial filter method.

Next, FIGS. 14A and 14B show the relationship among the hole position information, the through holes, and the hole mask image in the hole information memory section. As shown in FIG. 14A, the through hole 9 of the hole measurement signal obtained in the hole measurement recognition unit.
1, the hole center coordinate Y of the hole position information is ± 100 μm
Is defined as an area 425 of the hole recognition valid signal. And if this area overlaps the center of the through hole,
As shown in FIG. 14B, a hole mask image for the through hole is created.

Next, FIG. 15 shows the process of registering the hole position information in the hole information memory section. The figure shows a case where hole position information is registered based on a hole substrate. In the figure, steps S101 to S103 are performed by the master C.
The hole processing CPU unit executes it in accordance with an instruction from the PU.

Of these, the step of S103 (setting of the "hole determination section") is an important point in this work.
That is, since there are only the same drill holes as through holes on the hole substrate, it is desirable that the number of continuous OKs is 8 perfect circles. Also, since it is the hole information registration process, the hole recognition valid signal is irrelevant. The hole should be determined only from the information of the measurement signal, and the above setting is performed in the step of S103.
S104 to S107 are hardware processes. S10
Reference numerals 8 and 109 are processes of the hole processing CPU for the master CPU.

Next, FIGS. 16 and 17 show hole recognition master processing in the hole mask image creation and inspection section from the hole position information. In both figures, S201 to S205
Is executed by the hole processing CPU based on an instruction from the master CPU. Further, S206 to S216 are hardware processes. As described above, according to this example, a through hole can be accurately detected to create a true hole mask image, and at the same time, it can be realized only by adding a hole recognition mask processing unit to the conventional inspection machine, and therefore the cost is also reduced. cheap.

Example 2 In this example, an example of measuring a non-through hole together with a through hole will be described. That is, the printed wiring board has non-through holes in addition to conductive through holes.

The non-through hole is only a drill hole, and the purpose of its existence is to screw a screw hole for a component,
Perforations and the like for dividing the sheet into pieces in a later process. For this reason, there is no wiring pattern to be inspected around the non-through hole. Moreover, since it is only a drill hole, it is basically impossible to image by the reflected light method, and it can be said that there is no particular problem in the defect shape inspection of the printed wiring board.

However, when the edge of the non-through hole 80 is whiter than the surroundings as shown by reference numeral 84 in FIG. 18A, only the edge portion is shown by reference numeral 85 in FIG. 18B. Sometimes it appears on the binary image. This edge information may be erroneously determined as a residual copper or a line break. Therefore, masking of this part may be necessary.

Therefore, in this embodiment, as shown in FIG. 19, the hole recognition mask processing section 4 (FIG. 1) according to the present invention.
In parallel with this, the mask processing unit 48 is provided only for the non-through holes. The non-through hole mask processing unit 48 creates a hole mask (hole mask image) by the hole position method shown in the above-mentioned conventional example.

Since the non-through hole does not receive the reflected light from the land like the through hole, the above hole position method can be adopted. As a problem of the hole position method, it is necessary to make the hole mask image larger than the drill hole diameter, but in the case of a non-through hole, there is no pattern to be inspected in the vicinity, so there is no problem.

The hole mask image for through hole and the hole mask image for non-through hole are the hole mask synthesizing unit 4
In 80, the holes are masked and the hole mask is sent to the inspection unit 31, and is subjected to the defect shape inspection of the wiring pattern as in the first embodiment. According to this example, accurate hole mask images can be applied to both through holes and non-through holes.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a printed wiring board inspection apparatus according to a first embodiment.

FIG. 2 is an explanatory diagram of measurement of a hole measurement recognition unit according to the first embodiment.

FIG. 3 is an explanatory diagram of signal processing of a hole measurement recognition unit according to the first embodiment.

FIG. 4 is a circuit schematic diagram of a pixel extraction portion of a hole measurement recognition unit in the first embodiment.

FIG. 5 is an explanatory diagram showing the positional relationship of the extracted pixels of the hole measurement recognition unit in the first embodiment.

FIG. 6 is a circuit schematic diagram of a measurement recognition part of an extracted pixel of a hole measurement recognition part in the first embodiment.

FIG. 7 is an explanatory diagram of encoder processing of extracted pixels of a hole measurement recognition unit according to the first embodiment.

FIG. 8 is a code explanatory diagram of an encoder process of a hole measurement recognition unit in the first embodiment.

FIG. 9 is an explanatory diagram of a hole information memory unit according to the first embodiment.

FIG. 10 is an explanatory diagram of a hole recognition area generation unit according to the first embodiment.

FIG. 11 is an explanatory diagram of a hole determination unit according to the first embodiment.

FIG. 12 is an explanatory diagram of hole determination in the hole determination unit according to the first embodiment.

FIG. 13 is an explanatory diagram of a hole mask generation unit according to the first embodiment.

FIG. 14 is an explanatory diagram showing a relationship between a through hole, a hole recognition valid signal, and a hole mask image in the first embodiment.

FIG. 15 is a flowchart showing registration of hole position information according to the first embodiment.

FIG. 16 is a flowchart of hole recognition mask processing in the first embodiment.

FIG. 17 is a flowchart following FIG. 16;

FIG. 18 is an explanatory diagram of non-through holes according to the second embodiment.

FIG. 19 is a block diagram according to the second embodiment.

FIG. 20 is an explanatory view of through holes and lands in a conventional example.

FIG. 21 is an explanatory diagram of a hole position method in a conventional example.

FIG. 22 is an explanatory diagram of a conventional hole recognition method.

[Explanation of symbols]

 10 ... Printed wiring board, 21 ... Imaging device, 4 ... Hole recognition mask processing section, 41 ... Hole measurement recognition section, 42 ... Hole information memory section, 91 ... Through hole, 92 ... Land, 921 ... Remaining seat, 923 ... Out of seat, 93 ... Lead wire,

Claims (1)

[Claims] 1. An image pickup device for reading a wiring pattern on a printed wiring board which is a product substrate to be inspected, and whether or not it is true defect data based on a pattern image from the image pickup device and a hole mask image described later. The hole recognition mask processing section is composed of an inspection section for selecting whether or not, a hole recognition mask processing section provided between the imaging device and the inspection section, and a data totaling means for totaling the defect data. A hole measurement recognition unit for measuring the continuity of the base material level image based on the pattern image and for recognizing that it is a hole, a hole measurement signal from the hole measurement recognition unit, and a hole recognition area generation unit described later. And a hole detection signal from the hole determination section and a hole detection section that outputs a hole detection signal by making a final hole determination by comparing and collating both signals. ，
A hole mask image for making a mask on the hole portion in the pattern image is prepared, and a hole mask generation unit for transmitting the hole mask image to the inspection unit and hole position information indicating the position of the hole on the printed wiring board are recorded. A hole information memory unit to be input and hole position information of the hole information memory unit are input and expanded by a necessary correction amount, and a hole recognition valid signal for selecting true hole detection information from the hole measurement signal is provided. An inspection apparatus for a printed wiring board, comprising: a hole recognition area generation unit for transmitting to the hole determination unit.